Actuator

ABSTRACT

An actuator includes a quick release inserted in a transmission between an activating element ( 6 ) and a reversible electric motor ( 2 ) for releasing the activating element from the electric motor and the part of the transmission extending from the motor to the quick release. The quick release comprises two cylindrical coupling parts ( 8, 9 ) surrounded by a coupling spring ( 11 ) having outwardly bent ends, said ends being connected with their respective cylindrical elements ( 12, 13 ), seated to take part in the rotation of the coupling under normal circumstances, and wherein the two cylindrical elements ( 12, 13 ) with a release ( 14 ) are adapted to being rotated mutually to turn the ends of the spring away from each other, such that the spring ( 11 ) is released from at least one of the coupling ( 8, 9 ) for complete or partial release of the coupling. The two cylindrical elements ( 12, 13 ) are provided with an exterior toothing, and that the release ( 14 ) has a corresponding toothing ( 20 ) which may be caused to mesh therewith for mutual rotation of the cylinders.

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION THE PRIOR ART

An actuator having such quick release function is known from EP 0 685662 to Linak A/S, and the present invention is a further development ofthis.

The example given in EP 0 685 662 of operating the quick releasefunction is based on two cylindrical elements, where one with a Y-shapedrocker arm can be urged into the other, whereby the two cylinders due toa guideway are rotated in relation to each other. As a result thecoupling spring is released, as its outwardly bent ends engaging tracksin the cylinders are rotated away from each other, causing the couplingspring to expand and thereby release its grip around the cylindricalcoupling parts.

The present invention provides a different solution to operating thecoupling.

SUMMARY OF THE INVENTION

The invention is characterized in that the two cylindrical elements areprovided with an exterior toothing, and that the release has acorresponding toothing which may be caused to mesh therewith for mutualrotation of the cylinders. Hereby it is possible to construct the quickrelease just as short as the coupling spring used. In contrast, thequick release according to EP 0 685 662 is longer, as one of thecylindrical elements extends a distance beyond the spring. According tothe invention, both cylindrical elements may be contained within thelength of the spring, they may even be made shorter. There is theadditional advantage that the elements may be identical. However, it ispreferred that the elements abut each other and are formed with mutualguides.

The toothing may either be located on the curved surface of thecylinders or on the end faces thereof, the first mentioned locationbeing preferred as this is obviously the simplest. Irrespective of thelocation, it will be understood that the extent of the toothing may belimited according to the desired movement. On the other hand, thesimplest thing is that the toothing extends all the way around. On thecurved surface, however, it may be an advantage to limit the width ofthe toothing according to the width of the release, such that the restof the surface may be used for other purposes such as guide or brakingsurface.

The release may be designed as two separate elements which activatetheir respective cylindrical elements, but this basically complicatesthe construction.

A Y-shaped release where a first leg and a second leg are formed with atoothing which may be caused to mesh with the toothing on the one or theother cylindrical element, respectively, simplifies the construction andmay be used in connection with a toothing on the curved surfaces of thecylindrical elements as well as on the end faces. With a toothing on theend faces directed toward each other, the release is arranged betweenthe two cylindrical elements, otherwise the release rides over the twocylindrical elements in the longitudinal direction. Axial displacementof the release will then cause the two cylinders to rotate in oppositedirections.

The construction may be configured such that the Y-shaped release, froma retracted position, is laterally displaced into mesh with thecylindrical elements. When the legs have a smooth portion from theirdividing point and a distance downwards and with the toothing arrangedon the outer part of the legs, the release may be seated down over thecylinders, and pulling thereof may cause the toothing to mesh with thecylindrical elements.

To avoid unintentional release of the quick release the release isspring-loaded to assume a rest position, where the toothing is not inmesh with the cylindrical elements.

This presents at the same time the possibility of operating the releaseby means of a cable. By pulling the cable the coupling may be completelydisengaged, i.e. that the connection is completely interrupted.Alternatively, the coupling may be released in a controlled manner suchthat a partial release of the coupling is achieved, resulting in acontrolled movement of the activating element. The cable may be mounteddirectly or indirectly on the release. In case the cable in theapplication of the actuator is in direct extension of the release, it isexpedient to mount the cable directly on the release. If, on the otherhand, the direction of the cable is perpendicular to the release, thenthe connection may be established by a mechanism which, when beingoperated, converts a rotary movement or an axial movement into amovement perpendicular thereto. An example are mechanisms based on aspindle and nut or a wedge-shaped disc.

BRIEF DESCRIPTION OF THE DRAWINGS

A linear actuator according to the invention will be described in moredetail in the following with reference to the accompanying drawing, inwhich:

FIG. 1 shows a longitudinal section through the actuator,

FIG. 2 shows a cross-section through the actuator, and

FIG. 3 shows an enlarged view of the release for the quick release.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in the drawings, the main parts of the actuator are constitutedby a housing 1 with a reversible electric motor 2 which, through a wormgear, drives a spindle 4 having a spindle nut 5 to which an activationrod 6 surrounded by an outer tube 7 is attached. The actuator is of thesame type as described in the international application WO 02/29284 A1to Linak A/S, and reference is made thereto.

The actuator has a quick release function comprising two coupling parts8,9, where one part 8 is fitted permanently on the spindle, while theother part 9 is fitted permanently on the worm wheel 10 of the wormgear. More precisely, the side of the worm wheel facing the front end ofthe actuator is constructed with a cylindrical section, upon which abushing with a corbie-step is fixed. The coupling part 8 on the spindleis constructed with a bowl which is seated over this corbie-step. Acoupling spring 11 is fitted around the two parts 8,9, extending betweenthe side of the worm wheel and a collar on the coupling part 8. Innormal conditions, the spring 11 couples the two coupling parts 8,9together, such that the spindle is connected to the motor via the wormgear.

Around the coupling spring 11 there are two cylindrical elements 12,13provided with an exterior toothing. The ends of the coupling spring 11are bent radially outwards and are embedded in their respectiveelements.

A Y-formed release 14 rides with its legs over the two cylindricalelements 12,13 such that one leg is opposite to one element, while theother leg 15 is seated down over the other element 13. The upper portionof the legs is smooth, while the lower portion is provided with atoothing to engage the toothing on the elements 12,13.

The neck 16 of the Y-formed release 14 is controlled in a sleeve 17fixed to the housing. On the neck there is a spring 18 which tightensbetween a shoulder in the opening of the sleeve and the upper side ofthe release, such that the release is spring-loaded in a parkingposition, where the lowest, toothed part of the legs is out of contactwith the two cylindrical elements 12,13. A cable 19 connected to aoperating handle (not shown) is fixed to the top end of the neck.

When the handle is pulled, the release is pulled up, as shown in FIG. 2,until the lower toothed part 20 of the legs engages the respectivecylindrical elements 12,13, which are then turned opposite each other.The ends of the spring will then be pulled from each other, oneclockwise and the other counterclockwise. In this way the spring willexpand, i.e. its internal diameter will increase and the two couplingparts 8,9 are then released. The spindle will then be released and canrotate freely. If the activation rod 6 is under load and if it is in anextended position, it will then be pushed inwards, depending on the loadbeing able to overcome the self-locking ability of the spindle.

Although the embodiment relates to a linear actuator, it is obvious, asis also apparent from the claims, that the invention is also applicablein rotary actuators, e.g. of the type described in WO 01/17401 A1 toLinak A/S.

1. An actuator, wherein a quick release is inserted in a transmissionbetween an activating element and a reversible electric motor forreleasing the activating element from the electric motor and a part ofthe transmission extending from the motor to the quick release, saidquick release comprising two cylindrical coupling parts surrounded by acoupling spring having outwardly bent ends, said ends being connectedwith respective cylindrical elements, seated to take part in therotation of the coupling under normal circumstances, and wherein the twocylindrical elements with a release are adapted to being rotatedmutually to turn the ends of the spring away from each other, such thatthe spring is released from at least one of the coupling parts forcomplete or partial release of the coupling, wherein the two cylindricalelements are provided with an exterior toothing, and wherein the releasehas a corresponding toothing which may be caused to mesh therewith formutual rotation of the cylinders.
 2. An actuator according to claim 1,wherein the cylindrical elements include a toothing on curved surfacesthereof.
 3. An actuator according to claim 2, wherein the cylindricalelements include a toothing on an end face.
 4. An actuator according toclaim 2, wherein the toothing is annular.
 5. An actuator according toclaim 2, wherein a width of the toothing only extends over a portion ofthe length of the cylinders.
 6. An actuator according to claim 1,wherein the release is Y-shaped, where a first leg and a second leginclude a toothing which may be caused to contact the toothing on theone or the other cylindrical element, respectively.
 7. An actuatoraccording to claim 6, wherein the legs have a smooth portion from theirdividing point and a distance downwards, while the toothing is arrangedon a distal part of the legs.
 8. An actuator according to claim 7,wherein the release is spring-loaded to assume a rest position, wherethe toothing is out of mesh with the cylindrical elements.
 9. Anactuator according to claim 8, wherein the release is connected directlyor indirectly with a cable provided with an operating handle.